Contraindre l'augmentation en dioxyde de carbone (CO2) lors des déglaciations basés sur son rapport isotopique stable du carbone (δ13CO2)
Year: 2008
Type: dissertation
Abstract: The present work is based on the measurement of carbon dioxide (CO2) and its stable isotopic ratio δ13CO2 in air bubbles trapped in polar ice (EPICA core, Dome C, in Antartica, EDC). We focus on rapid transitions from glacial to interglacial periods. δ13CO2 allows the partitioning of the origin of CO2 between oceanic and terrestrial sources. This study documents with high temporal resolution the evolution of CO2 and δ13CO2 during the two last deglaciations. The last deglaciation is characterized by an increase of 80 ppmv CO2, coeval with a decrease of 0.6 ‰ in δ13CO2. Larger amplitudes were observed during the penultimate deglaciation (+110 ppmv CO2 with a 0.9 ‰ decrease in δ13CO2). The measurements, interpreted with two carbon cycle models (BOXKIT and BICYCLE) are consistent with the following scenario. First, a Southern Hemisphere warming triggers an increase in atmospheric CO2. This provokes a biological and physical reorganization of the Southern Ocean which reduces δ13CO2. Last, this reorganization propagates to the north with a delayed impact of terrestrial biosphere during the Bølling/Allerød (B/A). These results obtained for the first time from the EDC core allowed to propose a scenario on the causes of deglaciations. A series of tests, based on ice of different properties, provided a validation of our extraction method.
Source: HAL
Author: A. Lourantou
Language: French
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
SDG: Climate action
Open Access status: green
OpenAlex ID: W149742257